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A Holistic Approach to Road Construction and Environmental Impact, and the Role of Ecologically Based Techniques in Planning and Design

A Holistic Approach to Road Construction and Environmental Impact, and the Role of Ecologically Based Techniques in Planning and Design

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    Halsema Highway Halsema Highway Document Transcript

    • CONFIDENTIAL PRIVATE INFORMATION International Forum on Life-Cycle Maintenance and Management Technologies for Smart Highway System A Holistic Approach to Road Construction and Environmental Impact, and the Role of Ecologically Based Techniques in Planning and Design Authors: Steven B Finnie and Harold T M Insley • Steven B Finnie Associate Director, Pavement, Trackbed and Materials Consultancy URS Scott Wilson Ltd, Nottingham, United Kingdom • Harold T M Insley Associate Director, Head of Environmental Services URS Scott Wilson, Hong Kong Highway Challenges 2
    • CONFIDENTIAL PRIVATE INFORMATION Contents of Presentation Theme of paper: Mountain Highways in Developing Countries • Halsema Highway Case Study • Typical Slope Problems • Design of Remedial Works • Environmental Aspects • Examples of other Mountain Road Projects • Typical Design Features Highway Challenges 3 Halsema Highway History • Road at 2,000m elevation and above • Typical rainfall 2,400mm per year • Partially paved mountain road damaged by earthquake and typhoons in1990s • Richter 7.8 magnitude quake in July 1990 seriously damaged road, and Hyatt Hotel in Baguio collapsed killing 80 people • Damage to road not immediately repaired • Significant typhoons caused major erosion damage • Consultants appointed in 1996 for feasibility study to rehabilitate highway • World Bank funded Highway Challenges 4
    • CONFIDENTIAL PRIVATE INFORMATION Major Arterial Highway serving Region • Halsema Highway runs from Baguio City to Bontoc to Banaue (rice terraces) • Baguio City regional capital • Major vegetable growing area • Vegetables trucked down to outskirts of Baguio in small trucks • Transferred to 10 wheeler trucks or bigger for transport to Manila (capital city) • Construction on first section from La Trinidad to Mount Data started in 2000 Highway Challenges 5 Feasibility Study, Rehabilitation Design and Construction Supervision • 180 km long Halsema Highway links Philippines summer capital of Baguio with famous “ Banaue rice terraces” World Heritage Site considered to be more than 2,000 years old • Road crosses some of most difficult topography in South East Asia – main ridge of Central Cordillera runs approximately north-south • Central Cordillera: steep, knife-edged and underlain by highly fractured, faulted and weathered materials • Scott Wilson carried out feasibility study, design and construction supervision of geotechnical works • Scope of services included geotechnical, geological, bio-engineering, hydrological, environmental, ecological and social impact aspects Highway Challenges 6
    • CONFIDENTIAL PRIVATE INFORMATION Halsema Highway, Philippines • Rural highway in high rainfall, seismically active mountainous area • Carried out feasibility study for rehabilitation including geotechnical, hydrological, environmental and social impact investigations • Although Halsema Highway is a major road, it is classed as a “low- cost” road for purposes of this rehabilitation, which restricted scope of investigations (i.e. limited ground investigation) and scope of rehabilitation work Highway Challenges 7 Halsema Highway, Philippines • Landscape very fragile, and highly susceptible to erosion caused by intense storm runoff and destabilising earthquakes • Programme of aerial photography carried out • Followed by field mapping, engineering geological inspection and the sinking of boreholes • Initial Environmental Assessment carried out • Innovative bio-engineering designs needed to stabilise slopes Highway Challenges 8
    • CONFIDENTIAL PRIVATE INFORMATION One of “Most Dangerous Roads in World” Highway Challenges 9 Typical Slope Problems • Failure of slopes on to road (rock falls, debris slides etc) • Failure of slopes below road Technical Assistance for Risk Assessment and Management D2 282800 in 1997 Leading to loss of road edge (including wall foundation failure) • Failure of entire road formation • Debris flows & slope erosion Highway Challenges 10
    • CONFIDENTIAL PRIVATE INFORMATION Large Landslide below Highway Highway Challenges 11 Unstable Slopes above Highway Highway Challenges 12
    • CONFIDENTIAL PRIVATE INFORMATION “Temporary” Structures to Maintain Access • After earthquake and typhoons in 1990s access along highway provided with mixture of “temporary measures” including Bailey Bridges, and temporary diversions • Photo of crossing of “saddle” where roadway failed on both sides of highway Highway Challenges 13 Design of Remedial Measures Integrated Approach Required • Geotechnical engineering measures • Drainage engineering measures and erosion control • Slope protection and bio-engineering measures • Environmental protection Highway Challenges 14
    • CONFIDENTIAL PRIVATE INFORMATION Typical Rehabilitation Halsema Highway Highway Challenges 15 Typical Major Rehabilitation Halsema Highway Highway Challenges 16
    • CONFIDENTIAL PRIVATE INFORMATION Integration of Bio-Engineering with Geotechnical Design Highway Challenges 17 Failures and Erosion below Road Bench Pre-Construction Highway Challenges 18
    • CONFIDENTIAL PRIVATE INFORMATION Rehabilitation below Road Bench Works Substantially Complete Highway Challenges 19 Masonry Wall to Support Road Bench Highway Challenges 20
    • CONFIDENTIAL PRIVATE INFORMATION Drainage and Stream Protection Measures Highway Challenges 21 Above Road Retaining Structure Completion of shotcrete & construction of above-road retaining structures Highway Challenges 22
    • CONFIDENTIAL PRIVATE INFORMATION Environmental Aspects • Environmental Impacts related to Heritage Sites and National Park • Construction Impacts • Traffic Related Impacts • Social Impacts Highway Challenges 23 Environmental Impacts – Heritage Sites and National Park • Photo shows rice terraces near Banaue • Heritage site • Road also passes through National Park • World Bank required impacts on Heritage Site and National Park minimised as far as practical Highway Challenges 24
    • CONFIDENTIAL PRIVATE INFORMATION Construction Impacts • Noise (generated by construction plant) • Dust • Disposal of excavated material • Excavation of borrow areas • Water quality impacts, and erosion • Social impacts from clearance, etc. • Impact of construction on traffic using road Highway Challenges 25 Traffic Related Impacts • Improved road surface, previously unpaved, now concrete pavement, results in increased vehicle speeds • Increased speeds result in greater potential for accidents involving excessive speeds • Accidents as a result of “blind” corners, pedestrians on roads, boulders from slopes above causing obstacle on road, fog banks • Mountain road creates opportunity for major accidents with vehicles crashing off road, and causing many fatalities (especially buses) • Limited budget for road side barrier but small up stand wall included • Road humps to reduce speed • Increased axle loads Highway Challenges 26
    • CONFIDENTIAL PRIVATE INFORMATION Social Impact Assessment • Clearance of encroachments into road reserve • Some acquisition of agricultural land for minor alignment improvements • Socio-Economic Surveys carried out • Resettlement Action Plan prepared • Community engagement Highway Challenges 27 Examples of Other Mountain Road Projects • Nepal: Prithvi Highway • Nepal: Third Road Improvement Project • Tajikistan: Shagon-Zigar Road • Bhutan: Road Network Study • Ethiopia: Koombolcha – Mekane Salem – Gundewien Road Highway Challenges 28
    • CONFIDENTIAL PRIVATE INFORMATION Prithvi Highway, Nepal Flood Damage Assessment, Study Report, Design of Remedial Works and Supervision • Geotechnical examination, inventory of flood damage • Recommendations for and prioritisation of reinstatement and further erosion protection works • Remedial, reinstatement, and protection measures • Design/supervision/ contract management services for damage repair, contract management and supervision Highway Challenges 29 Third Road Improvement Project, Nepal Improvement and Rehabilitation of Rural Roads • Improvement and rehabilitation of 350km of rural access road to bitumen standard in mountainous and flat terrain • Economic screening study • Typical design details, and design checks • Procurement and construction supervision Highway Challenges 30
    • CONFIDENTIAL PRIVATE INFORMATION Shagon-Zigar Road, Tajikistan Feasibility, Design, Supervision • Situated along border with Afghanistan, alignment through foothills of Pamirs and bordered by Pyanj River to east • Alignment traverses extremely rugged, mountainous terrain • Challenges to engineering team included rockfall from natural slopes, extreme topography and weather conditions and sensitive ground conditions disturbed by pre-contract blasting and seismic activity Highway Challenges 31 Road Network Study, Bhutan Technical Assistance Project to Prepare Prioritised Road Improvement Programme • Survey and analysis of typical slope stability problems • Slope maintenance manual • Economic evaluation of proposed improvements • Environmental Impact Assessment of proposed improvements • Road improvement strategies Highway Challenges 32
    • CONFIDENTIAL PRIVATE INFORMATION Kombolcha – Mekane Salem – Gundewien Road, Ethiopia Remote Sensing, Engineering Geological Mapping, Ground Investigation, Design Review (including redesign) and Construction Supervision • Construction of 136 km new gravel road, with dense base macadam on steep gradients, and simultaneous construction of 2 new bridges over River Nile and tributary, Difarsa River • Geotechnical services included detailed aerial photograph interpretation, field engineering geological and geomorphological mapping, reference condition mapping, landscape evolution modelling, ground investigation and outline design of slope works. Highway Challenges 33 Typical Design Features • Bio-engineering • Gabion Wall • Combined Masonry and Gabion Wall • Reinforced Earth Wall • Reinforced Concrete Grid Wall • Surface Reinforcement • Buttress Wall Highway Challenges 34
    • CONFIDENTIAL PRIVATE INFORMATION Bio-Engineering Slope Protection Bio-engineering is the use of vegetation, either alone or in conjunction with civil engineering structures, to reduce slope instability and erosion on slopes. 4 main groups of techniques are available: Grass line planting Brush layering etc Shrub, tree and bamboo planting Composite techniques Highway Challenges 35 Bio-engineering • Low construction cost • Low maintenance cost • Visually preferable • Contributes to local economy • Species selection is key: • Hardy • High rainfall and drought resistant • Extensive use of grasses • Bamboo and Shrub species with strong root network • Pine trees • Pilot trials • Indigenous and imported species • Local expertise utilised Highway Challenges 36
    • CONFIDENTIAL PRIVATE INFORMATION Gabion Wall Above Road: Gabion Wall in Nepal Below Road: Gabion Wall in Ethiopia Highway Challenges 37 Combined Masonry and Gabion Wall Construction Substantially Complete Pre-Construction Highway Challenges 38
    • CONFIDENTIAL PRIVATE INFORMATION Reinforced Earth Wall Under construction (Ethiopia) Highway Challenges 39 Reinforced Earth Wall Completed wall (Ethiopia) Highway Challenges 40
    • CONFIDENTIAL PRIVATE INFORMATION Reinforced Concrete Grid Wall Reinforced Concrete Grid Wall comprising Reinforced Concrete Members with Mortared Masonry Panels on Halsema Highway Highway Challenges 41 Surface Reinforcement “Plastering” a thin concrete layer over decomposed rock slope in Laos Highway Challenges 42
    • CONFIDENTIAL PRIVATE INFORMATION Buttress Wall Buttress wall under construction in Sri Lanka Highway Challenges 43